Tissue-Removing Catheter with Guidewire Isolation Liner

ABSTRACT

A tissue-removing catheter for removing tissue in a body lumen includes an elongate body having an axis, and proximal and distal end portions spaced apart from one another along the axis. The elongate body is sized and shaped to be received in the body lumen. A tissue-removing element is mounted on the distal end portion of the elongate body. The tissue-removing element is configured to remove the tissue as the tissue-removing element is rotated by the elongate body within the body lumen. An inner liner is received within the elongate body and defines a guidewire lumen. The inner liner is coupled to the tissue-removing element at a distal end portion of the inner liner. A coupling assembly is disposed in the tissue-removing element for coupling the inner liner to the tissue-removing element. The coupling assembly includes a bushing attached directly to the distal end portion of the inner liner.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patent application Ser. No. 15/970,736, which was filed May 3, 2018, which claims the benefit of, and priority to, U.S. Provisional Application Ser. No. 62/500,867, which was filed May 3, 2017, and U.S. Patent Application Ser. No. 62/500,879, which was filed May 3, 2017, each of which is incorporated herein by reference in its entirety for all purposes.

FIELD

The present disclosure generally relates to a tissue-removing catheter, and more particular, to an isolation liner and tissue-removing element for a tissue-removing catheter.

BACKGROUND

Tissue-removing catheters are used to remove unwanted tissue in body lumens. As an example, atherectomy catheters are used to remove material from a blood vessel to open the blood vessel and improve blood flow through the vessel. This process can be used to prepare lesions within a patient's coronary artery to facilitate percutaneous coronary angioplasty (PTCA) or stent delivery in patients with severely calcified coronary artery lesions. Atherectomy catheters typically employ a rotating element which is used to abrade or otherwise break up the unwanted tissue.

SUMMARY

In one aspect, a tissue-removing catheter for removing tissue in a body lumen generally comprises an elongate body having an axis, and proximal and distal end portions spaced apart from one another along the axis. The elongate body is sized and shaped to be received in the body lumen. A tissue-removing element is mounted on the distal end portion of the elongate body. The tissue-removing element is configured to remove the tissue as the tissue-removing element is rotated by the elongate body within the body lumen. An inner liner is received within the elongate body and defines a guidewire lumen. The inner liner is coupled to the tissue-removing element at a distal end portion of the inner liner. A coupling assembly is disposed in the tissue-removing element for coupling the inner liner to the tissue-removing element. The coupling assembly comprises a bushing attached directly to the distal end portion of the inner liner.

In another aspect, a tissue-removing catheter for removing tissue in a body lumen generally comprises an elongate body having an axis, and proximal and distal end portions spaced apart from one another along the axis. The elongate body is sized and shaped to be received in the body lumen. A tissue-removing element is mounted on the distal end portion of the elongate body. The tissue-removing element is configured to remove the tissue as the tissue-removing element is rotated by the elongate body within the body lumen. An inner liner is received within the elongate body and defines a guidewire lumen. The inner liner is coupled to the tissue-removing element at a distal end portion of the inner liner. A coupling assembly is disposed in the tissue-removing element for coupling the inner liner to the tissue-removing element. The coupling assembly comprises a bushing attached to the distal end portion of the inner liner. The bushing includes a center ring portion, a proximal ring portion extending proximally from the center ring portion, and a distal ring portion extending distally from the center ring portion. The distal ring portion has a constant outer cross-sectional dimension extending along a length of the distal ring portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation of a catheter of the present disclosure;

FIG. 2 is an enlarged elevation of a distal end portion of the catheter;

FIG. 3 is an enlarged elevation of a proximal end portion of the catheter;

FIG. 4 is an enlarged fragmentary longitudinal cross section of the distal end portion of the catheter in FIG. 2;

FIG. 5 is a cross section taken through line 5-5 in FIG. 2;

FIG. 6 is a fragmentary elevation of an isolation liner of the catheter with portions broken away to show internal details;

FIG. 7 is an enlarged longitudinal cross section of a tissue-removing element of the catheter;

FIG. 8 is a perspective of a bushing of the catheter;

FIG. 9 is a perspective of a first bearing of the catheter; and

FIG. 10 is a perspective of a second bearing of the catheter.

Corresponding reference characters indicate corresponding parts throughout the drawings.

DETAILED DESCRIPTION

Referring to the drawings, and in particular FIG. 1, a rotational tissue-removing catheter for removing tissue in a body lumen is generally indicated at reference number 10. The illustrated catheter 10 is a rotational atherectomy device suitable for removing (e.g., abrading, cutting, excising, ablating, etc.) occlusive tissue (e.g., embolic tissue, plaque tissue, atheroma, thrombolytic tissue, stenotic tissue, hyperplastic tissue, neoplastic tissue, etc.) from a vessel wall (e.g., coronary arterial wall, etc.). The catheter 10 may be used to facilitate percutaneous coronary angioplasty (PTCA) or the subsequent delivery of a stent. Features of the disclosed embodiments may also be suitable for treating chronic total occlusion (CTO) of blood vessels, and stenoses of other body lumens and other hyperplastic and neoplastic conditions in other body lumens, such as the ureter, the biliary duct, respiratory passages, the pancreatic duct, the lymphatic duct, and the like. Neoplastic cell growth will often occur as a result of a tumor surrounding and intruding into a body lumen. Removal of such material can thus be beneficial to maintain patency of the body lumen.

The catheter 10 is sized for being received in a blood vessel of a subject. Thus, the catheter 10 may have a maximum size of 3, 4, 5, 6, 7, 8, 9, 10, or 12 French (1, 1.3, 1.7, 2, 2.3, 2.7, 3, 3.3, or 4 mm) and may have a working length of 20, 30, 40, 60, 80, 100, 120, 150, 180 or 210 cm depending of the body lumen. While the remaining discussion is directed toward a catheter for removing tissue in blood vessels, it will be appreciated that the teachings of the present disclosure also apply to other types of tissue-removing catheters, including, but not limited to, catheters for penetrating and/or removing tissue from a variety of occlusive, stenotic, or hyperplastic material in a variety of body lumens.

Referring to FIGS. 1 and 2, the catheter 10 comprises an elongate outer layer 12 disposed around an elongate inner liner 14. The outer layer 12 and inner liner 14 extend along a longitudinal axis LA of the catheter from a proximal end portion 16 to a distal end portion 18 of the catheter. A tissue-removing element 20 is disposed on a distal end of the outer layer 12 and is configured for rotation to remove tissue from a body lumen as will be explained in greater detail below. A sheath 22 is disposed around the outer layer 12. The outer layer 12 and the inner liner 14 are both configured to translate relative to the sheath 22. The catheter 10 is sized and shaped for insertion into a body lumen of a subject. The sheath 22 isolates the body lumen from at least a portion of the outer layer 12 and inner liner 14. The inner liner 14 defines a guidewire lumen 24 (FIG. 5) for slidably receiving a guidewire 26 therein so that the catheter 10 can be advanced through the body lumen by traveling along the guidewire. The guidewire can be a standard 0.014 inch outer diameter, 300 cm length guidewire. In certain embodiments, the inner liner 14 may have a lubricious inner surface for sliding over the guidewire 26 (e.g., a lubricious surface may be provided by a lubricious polymer layer or a lubricious coating). In the illustrated embodiment, the guidewire lumen 24 extends from the proximal end portion 16 through the distal end portion 18 of the catheter 10 such that the guidewire 26 is extendable along an entire working length of the catheter 10. In one embodiment, the overall working length of the catheter 10 may be between about 135 cm (53 inches) and about 142 cm (56 inches).

The catheter 10 further comprises a handle 40 secured at the proximal end portion 16 of the catheter. The handle 40 supports an actuator 42 (e.g., a lever, a button, a dial, a switch, or other device) configured for selectively actuating a motor 43 disposed in the handle to drive rotation of the outer layer 12, and tissue-removing element 20 mounted at the distal end of the outer layer. The motor 43 is coupled to the outer layer 12 by a gear assembly 44 and a drive 48 supported by the handle 40. A slide or advancer 45 is positioned on the handle 40 and operatively coupled to the outer layer 12 for movement of the outer layer relative to the handle to advance and retract the outer layer and tissue-removing element 20. The handle 40 defines a slot (not shown) which limits the movement of the slide 45 relative to the handle. Thus, the length of the slot determines the amount of relative movement between the outer layer 12 and the handle 40. A perfusion port 46 may be disposed at the proximal end 16 of the catheter 10. The port 46 communicates with a space between the sheath 22 and the outer layer 12 for delivering fluid (e.g., saline) to cool the rotating outer layer during use. A proximal port 47 allows for passage of the guidewire 26 and inner liner 14 through the proximal end of the handle 40. A guidewire lock (not shown) may be provided on the handle 40 to lock the guidewire 26 in place relative to the handle.

It is understood that other suitable actuators, including but not limited to touchscreen actuators, wireless control actuators, automated actuators directed by a controller, etc., may be suitable to selectively actuate the motor in other embodiments. In some embodiments, a power supply may come from a battery (not shown) contained within the handle 40. In other embodiments, the power supply may come from an external source.

Referring to FIGS. 1 and 3, the outer sheath 22 comprises a tubular sleeve configured to isolate and protect a subject's arterial tissue within a body lumen from the rotating outer layer 12. The sheath 22 is fixed to the handle 40 at a proximal end of the sheath and does not rotate. A hub 52 mounted on the proximal end of the sheath 22 attaches the sheath to the handle 40. The hub 52 includes a locking feature 54 (e.g., threaded luer lock) for engaging the handle 40 to attach the sheath 22 to the handle. The sheath 22 provides a partial enclosure for the outer layer 12 and inner liner 14 to move within the sheath. The inner diameter of the sheath 22 is sized to provide clearance for the outer layer 12. The space between the sheath 22 and the outer layer 12 allows for the outer layer to rotate within the sheath and provides an area for saline perfusion between the sheath and outer layer. The outer diameter of the sheath 22 is sized to provide clearance with an inner diameter of a guide catheter (not shown) for delivering the catheter 10 to the desired location in the body lumen. A strain relief 56 is provided at the proximal end of the sheath 22 to alleviate tension applied to the proximal end of the sheath 22 as the sheath is bent during use of the catheter 10. In one embodiment, the sheath 22 has an inner diameter of about 0.050 inches (1.27 mm), an outer diameter of about 0.055 inches (1.4 mm), and a length of about 1500 mm (59 inches). The sheath 22 can have other dimensions without departing from the scope of the disclosure. In one embodiment, the outer sheath 22 is made from Polytetrafluorethylene (PTFE). Alternatively, the outer sheath 22 may comprise a multi-layer construction. For example, the outer sheath 22 may comprise an inner layer of perfluoroalkox (PFA), a middle braided wire layer, and an outer layer of Pebax.

Referring to FIGS. 1, 2, 4, and 5, the outer layer 12 may comprise a tubular stainless steel coil configured to transfer rotation and torque from the motor 43 to the tissue-removing element 20. Configuring the outer layer 12 as a coiled structure provides the outer layer with a flexibility that facilitates delivery of the catheter 10 through the body lumen. Also, the coil configuration allows for the rotation and torque of the outer layer 12 to be applied to the tissue-removing element 20 when the catheter 10 is traversed across a curved path. The stiffness of the outer layer 12 also impacts the ease at which the coil is traversed through the body lumen as well as the coil's ability to effectively transfer torque to the tissue-removing element 20. In one embodiment, the outer layer 12 is relatively stiff such that axial compression and extension of the coil is minimized during movement of the catheter 10 through a body lumen. The coil configuration of the outer layer 12 is also configured to expand its inner diameter when the coil is rotated so that the outer layer remains spaced from the inner liner 14 during operation of the catheter 10. In one embodiment, the outer layer 12 has an inner diameter of about 0.023 inches (0.6 mm) and an outer diameter of about 0.035 inches (0.9 mm). The outer layer 12 may have a single layer construction. For example, the outer layer may comprise a 7 filar (i.e., wire) coil with a lay angle of about 30 degrees. Alternatively, the outer layer 12 could be configured from multiple layers without departing from the scope of the disclosure. For example, the outer layer 12 may comprise a base coil layer and a jacket (e.g., Tecothane™) disposed over the base layer. In one embodiment, the outer layer comprises a 15 filar coil with a lay angle of about 45 degrees. The Tecothane™ jacket may be disposed over the coil. Alternatively, the outer layer 12 may comprise a dual coil layer configuration which also includes an additional jacket layer over the two coil layers. For example, the outer layer may comprise an inner coil layer comprising a 15 filar coil with a lay angle of about 45 degrees, and an outer coil layer comprising a 19 filar coil with a lay angle of about 10 degrees. Outer layers having other configurations are also envisioned.

Referring to FIGS. 1, 2, and 4-6, the inner liner 14 comprises a multiple layer tubular body configured to isolate a least a portion of the guidewire 26 from the outer layer 12 and tissue-removing element 20. The inner liner 14 is extendable through the handle 40 from a position proximal of the handle to a position distal of the handle. In one embodiment, the inner liner 14 is coupled to the handle 40 but is not fixedly attached to the handle 40 to allow translation of the inner liner relative to the handle. In this embodiment, rotation of the inner liner 14 is not prohibited. However, the clearance between the inner liner 14 and the outer layer 12, and the attachment of the inner liner to a coupling assembly 57 in the tissue-removing element 20 prevents any rotation of the inner liner caused by the rotation of the outer layer and tissue-removing element. In this embodiment, both the inner liner 14 and outer layer 12 are permitted to translate relative to the handle 40.

The inner liner 14 has an inner diameter that is sized to pass the guidewire 26. The inner liner 14 protects the guide wire from being damaged by the rotation of the outer layer 12 by isolating the guidewire from the rotatable outer layer. The inner liner 14 also extends past the tissue-removing element 20 to protect the guidewire 26 from the rotating tissue-removing element. Thus, the inner liner 14 is configured to prevent any contact between the guidewire 26 and the rotating components of the catheter 10. Therefore, any metal-to-metal engagement is eliminated by the inner liner 14. This isolation of the outer layer 12 and tissue-removing element 20 from the guidewire 26 also ensures that the rotation of the outer layer and tissue-removing element is not transferred or transmitted to the guidewire. As a result, a standard guidewire 26 can be used with the catheter 10 because the guidewire does not have to be configured to withstand the torsional effects of the rotating components. Additionally, by extending through the tissue-removing element 20 and past the distal end of the tissue-removing element, the inner liner 14 stabilizes the tissue-removing element by providing a centering axis for rotation of the tissue-removing element about the inner liner.

In the illustrated embodiment, the inner liner 14 comprises an inner PTFE layer 60, an intermediate braided layer 62 comprised of stainless steel, and an outer layer 64 of polyimide. The PTFE inner layer 60 provides the inner liner 14 with a lubricous interior which aids in the passing of the guidewire 26 though the inner liner. The braided stainless steel intermediate layer 62 provides rigidity and strength to the inner liner 14 so that the liner can withstand the torsional forces exerted on the inner liner by the outer layer 12. In one embodiment, the intermediate layer 62 is formed from 304 stainless steel. The outer polyimide layer 64 provides wear resistance as well as having a lubricous quality which reduces friction between the inner liner 14 and the outer layer 12. In one embodiment, the inner liner 14 has an inner diameter ID of about 0.016 inches (0.4 mm), an outer diameter OD of about 0.019 inches (0.5 mm), and a length of about 59 inches (1500 mm). The inner diameter ID of the inner liner 14 provides clearance for the standard 0.014-inch guidewire 26. The outer diameter OD of the inner liner 14 provides clearance for the outer layer 12 and tissue-removing element 20. Having a space between the inner liner 14 and the outer layer 12 reduces friction between the two components as well as allows for saline perfusion between the components.

Referring to FIGS. 1, 2, 5, and 7, the tissue-removing element 20 extends along the longitudinal axis LA from a proximal end adjacent the distal end portion of the outer layer 12 to an opposite distal end. The tissue-removing element 20 is operatively connected to the motor 43 for being rotated by the motor. When the catheter 10 is inserted into the body lumen and the motor 43 is rotating the tissue-removing element 20, the tissue-removing element is configured to remove occlusive tissue in the body lumen to separate the tissue from the wall of the body lumen. Any suitable tissue-removing element for removing tissue in the body lumen as it is rotated may be used in one or more embodiments. In the illustrated embodiment, the tissue-removing element 20 comprises an abrasive burr configured to abrade tissue in the body lumen when the motor 43 rotates the abrasive burr. The abrasive burr 20 has an abrasive outer surface formed, for example, by a diamond grit coating, surface etching, or the like. In other embodiments, the tissue-removing element can comprise one or more cutting elements having smooth or serrated cutting edges, a macerator, a thrombectomy wire, etc.

Referring to FIG. 7, a cavity 72 extends longitudinally through the tissue-removing element 20 such that the tissue-removing element defines openings at its proximal and distal ends. The cavity 72 includes a first diameter portion 74 extending distally from the proximal end of the tissue-removing element 20 and a second diameter portion 78 extending distally from the first diameter portion forming a first shoulder 80 disposed between the first and second diameter portions. A third diameter portion 82 extends distally from the second diameter portion 78 and forms a second shoulder 84 between the second and third diameter portions. A fourth diameter portion 86 extends distally from the third diameter portion to the distal end of the tissue-removing element and forms a third shoulder 88 between the third and fourth diameter portions. The diameters of the first, second, third, and fourth diameter portions 74, 78, 82, 86 are constant along their lengths. In the illustrated embodiment, a diameter D1 of the first diameter portion 74 is larger than a diameter D2 of the second diameter portion 78, the diameter D2 is larger than a diameter D3 of the third diameter portion 82, and the diameter D3 is larger than a diameter D4 of the fourth diameter portion 86. In one embodiment, the diameter D1 of the first diameter portion 74 is about 0.037 inches (0.95 mm), the diameter D2 of the second diameter portion 78 is about 0.035 inches (0.9 mm), the diameter D3 of the third diameter portion 82 is about 0.033 inches (0.85 mm), and the diameter D4 of the fourth diameter portion 86 is about 0.031 inches (0.8 mm). Other cross-sectional dimensions are also envisioned without departing from the scope of the disclosure.

Referring to FIGS. 4 and 7-10, a bushing 90 is received in the cavity 72 of the tissue-removing element 20 and around the inner liner 14. The busing 90 comprises a center ring portion 92, a proximal ring portion 94 extending proximally from the center ring portion, and a distal ring portion 96 extending distally from the center ring portion. The ring portions of the bushing 90 define a channel 99 extending through the bushing that receives a portion of the inner liner 14. In the illustrated embodiment, the center ring portion 92 has a larger outer diameter than the proximal and distal ring portions 94, 96. The center ring portion 92 is disposed in the second diameter portion 78 of the cavity 72, the proximal ring portion 94 is disposed in the first diameter portion 74, and the distal ring portion 96 is disposed in the second and third diameter portions 78, 82. In one embodiment, the bushing 90 is made from polyetheretherketone (PEEK) and polytetrafluoroethylene (PTFE). However, the bushing 90 can be formed from other material without departing from the scope of the disclosure.

A first bearing 98 is disposed around the proximal ring portion 94 of the bearing 90, and a second bearing 100 is disposed around the distal ring portion 96 of the bearing. The first bearing 98 has an outer diameter D5 that is greater than an outer diameter D6 of the second bearing 100. In one embodiment, the bearings 98, 100 are made from Zirconia. The first bearing 98 is disposed in registration with the first diameter portion 74 of the cavity 72 in the tissue-removing element 20 and seats between a distal end of the outer layer 12 at a proximal end of the first bearing, and the center ring portion 92 of the bushing 90 and first shoulder 80 at a distal end of the first bearing. The second bearing 100 is disposed in registration with the second diameter portion 78 of the cavity 72 and is seated between the second shoulder 84 at a distal end of the second bearing, and the center ring portion 92 of the bushing 90 at a proximal end of the second bearing. As such the bushing 90 and bearings 98, 100 are held within the cavity 72 of the tissue-removing element 20. Broadly, the bushing 90 and bearings 98, 100 may be considered a coupling assembly 57 for coupling the inner liner 14 to the tissue-removing element 20.

Referring to FIG. 4, an interior surface of the bushing 90 is fixedly attached to the inner liner 14 such that the inner liner is coupled to the tissue-removing element 20 through the bushing. In one embodiment an adhesive such as an epoxy glue bonds the bushing 90 to the inner liner 14. As such, the bushing 90 does not rotate around the inner liner 14. The outer layer 12 is directly and fixedly attached to the tissue-removing element 20. The tissue-removing element 20 can be fixedly attached to the distal end of the outer layer 12 by any suitable means. In one embodiment, adhesive bonds the outer layer 12 to the tissue-removing element 20. The outer layer 12 is received in the first diameter portion 74 of the cavity 72 and a distal end of the outer layer abuts the first bearing 98. However, the outer layer 12 is not directly attached to the bushing 90, bearings 98, 100, or inner liner 12. Thus, rotation of the outer layer 12 and tissue-removing element 20 is not transmitted to the inner liner 14 to also rotate the inner liner. Rather the tissue-removing element 20 rotates around the bushing 90 and bearings 98, 100. And because the inner liner is fixedly attached to the bushing 90, which is retained within the cavity 72 of the tissue-removing element 20 by the outer layer 12, the inner liner 14 is coupled to the outer layer through the bushing and bearing arrangement. Therefore, translational movement of the outer layer 12 is transmitted to the inner liner 14 such that the inner liner and outer layer will translate together when one of the inner layer and outer layer is advanced or retracted within the body lumen. This configuration prevents the outer layer 12 and tissue-removing element 20 from advancing past a distal end of the inner liner 14 and contacting the guidewire 26. As a result, a configuration where the inner liner 14 is not positioned to isolate the guidewire 26 from the outer layer 12 and tissue-removing element 20 is prevented.

The inner liner 14 extends through the outer layer 12 and past the distal end of the tissue-removing element 20. The fourth diameter portion 86 of the cavity 72 is sized to pass the inner liner 14 with a small clearance. The inner diameter D4 provides clearance between the tissue-removing element 20 and the inner liner 14 to reduce friction between the components. Accordingly, the tissue-removing element 20 is shaped and arranged to extend around at least a portion of the outer layer 12 and inner liner 14 and thus provides a relatively compact assembly for abrading tissue at the distal end portion of the catheter 10.

Referring to FIG. 7, an exterior surface of the body of the tissue-removing element 20 includes a proximal segment 102, a middle segment 104, and a distal segment 106. A diameter of the proximal segment 102 increases from the proximal end of the tissue-removing element 20 to the middle segment 104. The middle segment has a constant diameter and extends from the proximal segment 102 to the distal segment 106. The diameter of the distal segment 106 tapers from the middle segment 104 to the distal end of the tissue-removing element 20. A transition between the proximal segment 102 and the middle segment 104 forms a first angle α between the proximal and middle segments. In one embodiment, the angle α is less than about 170 degrees. In one embodiment, the angle α is about 165 degrees. Similarly, a transition between the middle segment 104 and the distal segment 106 forms a second angle β between the middle and distal segments. In one embodiment, the angle β is less than about 170 degrees. In one embodiment, the angle β is about 165 degrees. The tapered proximal and distal segments 102, 106 provide the tissue-removing element 20 with a general front and back wedge shaped configuration for wedging apart constricted tissue passages as it simultaneously opens the passage by removing tissue using the abrasive action of the tissue-removing element.

Referring to FIGS. 1 and 2, to remove tissue in the body lumen of a subject, a practitioner inserts the guidewire 26 into the body lumen of the subject, to a location distal of the tissue that is to be removed. Subsequently, the practitioner inserts the proximal end portion of the guidewire 26 through the guidewire lumen 24 of the inner liner 14 and through the handle 40 so that the guidewire extends through the proximal port 47 in the handle. The inner liner 14 may also extend through the handle 40 and out the proximal port 47. With the catheter 10 loaded onto the guidewire 26, the practitioner advances the catheter along the guidewire until the tissue-removing element 20 is positioned proximal and adjacent the tissue. When the tissue-removing element 20 is positioned proximal and adjacent the tissue, the practitioner actuates the motor 43 using the actuator 42 to rotate the outer layer 12 and the tissue-removing element mounted on the outer layer. The tissue-removing element 20 abrades (or otherwise removes) the tissue in the body lumen as it rotates. While the tissue-removing element 20 is rotating, the practitioner may selectively move the outer layer 12 and inner liner 14 distally along the guidewire 26 to abrade the tissue and, for example, increase the size of the passage through the body lumen. The practitioner may also move the outer layer 12 and inner liner 14 proximally along the guidewire 26, and may repetitively move the components in distal and proximal directions to obtain a back-and-forth motion of the tissue-removing element 20 across the tissue. During the abrading process, the bushing 90 and bearings 98, 100 couple the inner liner 14 to the outer layer 12 and allow the outer layer and tissue-removing-element to rotate around the inner liner. The inner liner 14 isolates the guidewire 26 from the rotating outer layer 12 and tissue-removing element 20 to protect the guidewire from being damaged by the rotating components. As such, the inner liner 14 is configured to withstand the torsional and frictional effects of the rotating outer layer 12 and tissue-removing element 20 without transferring those effects to the guidewire 26. Also, the coupling of the inner liner 14 and tissue removing element 20 allows for movement of the inner liner, such as translational movement within the body lumen, to be transmitted to the outer layer 12 and tissue-removing element to move outer layer and tissue-removing element through the body lumen with the inner liner. When the practitioner is finished using the catheter 10, the catheter can be withdrawn from the body lumen and unloaded from the guidewire 26 by sliding the catheter proximally along the guidewire. The guidewire 26 used for the abrading process may remain in the body lumen for use in a subsequent procedure.

When introducing elements of the present invention or the one or more embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

As various changes could be made in the above apparatuses, systems, and methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 

What is claimed is:
 1. A tissue-removing catheter for removing tissue in a body lumen, the tissue-removing catheter comprising: an elongate body having an axis, and proximal and distal end portions spaced apart from one another along the axis, wherein the elongate body is sized and shaped to be received in the body lumen; a tissue-removing element mounted on the distal end portion of the elongate body, the tissue-removing element being configured to remove the tissue as the tissue-removing element is rotated by the elongate body within the body lumen; an inner liner received within the elongate body and defining a guidewire lumen, the inner liner being coupled to the tissue-removing element at a distal end portion of the inner liner; and a coupling assembly disposed in the tissue-removing element for coupling the inner liner to the tissue-removing element, the coupling assembly comprising a bushing attached directly to the distal end portion of the inner liner.
 2. A tissue-removing catheter as set forth in claim 1, wherein the tissue-removing element is rotatable about at least a portion of the bushing.
 3. A tissue-removing catheter as set forth in claim 2, wherein the bushing receives a section of the inner liner within a channel of the bushing.
 4. A tissue-removing catheter as set forth in claim 3, wherein the bushing comprises a center ring portion, a proximal ring portion extending proximally from the center ring portion, and a distal ring portion extending distally from the center ring portion, the center ring portion having an outer cross-sectional dimension that is larger than an outer cross-sectional dimension of the proximal and distal ring portions.
 5. A tissue-removing catheter as set forth in claim 4, wherein the proximal ring portion, center ring portion, and distal ring portion each have constant outer cross-sectional dimensions extending along a length of the bushing.
 6. A tissue-removing catheter as set forth in claim 4, wherein the coupling assembly further comprises a bearing disposed around one of the proximal ring portion and the distal ring portion.
 7. A tissue-removing catheter as set forth in claim 6, wherein the bushing is made from polyetheretherketone (PEEK) and polytetrafluoroethylene (PTFE) and the bearing is made from Zirconia.
 8. A tissue-removing catheter as set forth in claim 1, wherein the bushing comprises a center ring portion, a proximal ring portion extending proximally from the center ring portion, and a distal ring portion extending distally from the center ring portion, the distal ring portion having a constant outer cross-sectional dimension extending along a length of the distal ring portion.
 9. A tissue-removing catheter as set forth in claim 8, wherein the distal ring portion has a constant outer cross-sectional dimension extending along an entire length of the distal ring portion.
 10. A tissue-removing catheter as set forth in claim 1, wherein a distal end of the inner liner extends distally of the tissue-removing element.
 11. A tissue-removing catheter for removing tissue in a body lumen, the tissue-removing catheter comprising: an elongate body having an axis, and proximal and distal end portions spaced apart from one another along the axis, wherein the elongate body is sized and shaped to be received in the body lumen; a tissue-removing element mounted on the distal end portion of the elongate body, the tissue-removing element being configured to remove the tissue as the tissue-removing element is rotated by the elongate body within the body lumen; an inner liner received within the elongate body and defining a guidewire lumen, the inner liner being coupled to the tissue-removing element at a distal end portion of the inner liner; and a coupling assembly disposed in the tissue-removing element for coupling the inner liner to the tissue-removing element, the coupling assembly comprising a bushing attached to the distal end portion of the inner liner, the bushing including a center ring portion, a proximal ring portion extending proximally from the center ring portion, and a distal ring portion extending distally from the center ring portion, the distal ring portion having a constant outer cross-sectional dimension extending along a length of the distal ring portion.
 12. A tissue-removing catheter as set forth in claim 11, wherein the distal ring portion has a constant outer cross-sectional dimension extending along an entire length of the distal ring portion.
 13. A tissue-removing catheter as set forth in claim 11, wherein the proximal ring portion, center ring portion, and distal ring portion each have constant outer cross-sectional dimensions extending along a length of the bushing.
 14. A tissue-removing catheter as set forth in claim 11, wherein the center ring portion has an outer cross-sectional dimension that is larger than an outer cross-sectional dimension of the proximal and distal ring portions.
 15. A tissue-removing catheter as set forth in claim 11, wherein the tissue-removing element is rotatable about at least a portion of the bushing.
 16. A tissue-removing catheter as set forth in claim 11, wherein the bushing includes a channel extending through the bushing, the bushing receiving a section of the inner liner within the channel of the bushing.
 17. A tissue-removing catheter as set forth in claim 16, wherein the coupling assembly comprises a bearing disposed around one of the proximal ring portion and the distal ring portion.
 18. A tissue-removing catheter as set forth in claim 16, wherein the bushing is made from polyetheretherketone (PEEK) and polytetrafluoroethylene (PTFE) and the bearing is made from Zirconia.
 19. A tissue-removing catheter as set forth in claim 11, further comprising a cavity extending through the tissue-removing element from a proximal end to a distal end of the tissue-removing element, wherein the bushing is disposed in the cavity.
 20. A tissue-removing catheter as set forth in claim 11, wherein a distal end of the inner liner extends distally of the tissue-removing element. 